On Friday 3 October, the European association of electricity transmission system operators (ENTSO-E) published its full preliminary report on the major blackout that occurred on 28 April in the Iberian Peninsula, described as “the most severe blackout incident on the European power system in over 20 years” and “the first ever of its kind”.
The report gives a detailed account of the situation on the electricity grid before the blackout, as well as the chronology of events and the various stages involved in restoring service, but explains that the root causes of the incident are still being identified. They will be the subject of a final report by ENTSO-E in the first quarter of 2026.
“Understanding events of this scale and complexity requires time and a rigorous technical and scientific approach”, says the European association.
The report stresses that “the high-voltage and low-frequency profiles in the Spanish transmission system led to cascading tripping of many other generators, both conventional and renewable”, confirming the observations of a report presented by the Spanish government on 17 June. The latter insisted on the “multifactorial origin” of the incident and acknowledged a lack of planning and foresight on the part of the electricity grid operator Red Eléctrica (see EUROPE 13662/17).
The ENTSO-E survey was carried out by a group of 45 experts from transmission system operators and European regulatory authorities, and was based on data collected from power plants, large electricity consumers and transmission and distribution system operators.
To see the full ENTSO-E preliminary report: https://aeur.eu/f/irc (Original version in French by Pauline Denys)